To compare effect of 2 different exogenous surfancts on neonatal mortality; compare effect of 2 different exogenous surfactants on the incidence and severity of acute RDS, air leak complications of RDS, and pulmonary hemorrhage;to compare the effect of 2 different exogenous surfactants on the incidence and severity of chronic lung disease and compare the effect of 2 different exogenous surfactants on the incidence of other RDS morbidities.